Single wafer type substrate cleaning method and apparatus

ABSTRACT

A single wafer type wet-cleaning apparatus for effectively preventing chemical fluids from flowing to the back face of a wafer when the back face thereof is wet-cleaned by chemical fluids, wherein purified water is injected and supplied to the back face of the wafer while a plurality of chemical fluids is sequentially supplied vertically from above to the wafer, which is rotatably supported, so that the purified water cleans the back face of the wafer and effectively prevents the chemical fluids from flowing to the back face of the wafer.

This application is division of prior application Ser. No. 09/948,800,filed Sep. 10, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a single wafer type substrate cleaning methodand a single wafer type substrate cleaning apparatus, more particularlyto a single wafer type wet cleaning technique or system for applying acleaning treatment to substrates such as semiconductor wafers one by oneduring the fabrication process as well as certain devices such aselectronic parts and the like.

2. Prior Art

A so-called batch type wet cleaning system has been the principal methodof cleaning substrates such as semiconductor wafers (hereinafterreferred to simply as “Wafers”), whereby wafers stored in a carriercassette are immersed in sequence in wet bench type cleaning bathsarranged in series, or wafers are directly immersed in the cleaningbaths through a transfer unit without being stored in a carriercassette. However, semiconductor devices have reached the sub micronage, in that they are now micro-fabricated and highly integrated, suchthat the face of wafers has recently required a very high degree ofcleaning density, and wafers which are not stored in a cassette have tobe wet-cleaned individually in a sealed cleaning housing. To this end, aso-called single wafer type wet cleaning system intended to meet therequirement of a higher cleaning density has been developed andproposed.

Under the single wafer type wet cleaning system, wafers can be cleanedwith the use of a simple and compact cleaning apparatus in a relativelyclean atmosphere where particles and the like do not settle or remain onthe face of the wafer. This system is therefore practical to use forsmall scale production.

Generally, under the single wafer type wet cleaning system, a cleaningtreatment is applied to the front face, i.e., the upper side surface ofthe wafer by various chemical fluids in a predetermined order. In theprocess, the chemical fluids supplied flows to the back face of thewafer, thereby possibly contaminating the back face of the wafer. If theback face of the wafer is contaminated, the handling jig for the wafer,e.g., the robot hands of a schalar type robot, also become contaminated,and as a result, other wafers which are handled by the same robot handsnaturally also get contaminated.

For the foregoing reason, a technique for preventing the chemicalfluid(s) from flowing to the back face of the wafer has become immenselydesirable, and the device shown in FIG. 7 providing such technique hasbeen proposed under Japanese Patent Laid Open Publication No.2000-343054 (hereinafter referred to as the “Chemical Fluid FlowingAround Prevention Technique”).

Under the Chemical Fluid Flowing Around Prevention Technique, chemicalfluid is supplied to the front face Wa of a wafer W while it isrotatably supported by a wafer rotary section “a”, and simultaneously acertain gas is supplied from an annular nozzle “b” under the wafer W soas to float the wafer W while it is prevented from sliding sideways by asupporter member “c”, so that the chemical fluid which has flowed fromthe front face Wa of the wafer W to the back face Wb thereof is blownoff as shown in FIG. 7(B).

However, the system of blowing off the chemical fluid through the supplyof a gas prevents the back face Wb of the wafer W from being cleaned,thereby making it difficult to completely avoid contamination of thewafer. Accordingly, a further improvement of the system is desirable.

SUMMARY OF THE INVENTION

The present invention has been made in view of the aforementionedproblem, and it is the object of the invention to provide a single wafertype wet-cleaning technique capable of effectively preventing chemicalfluids from flowing to the back face of the wafer, which is not storedin a cassette, when the front face thereof is wet-cleaned by chemicalfluids in a sealed cleaning chamber.

To achieve the above objective, the single wafer type cleaning method ofthe present invention for cleaning wafers which are not stored in acassette, one by one in a sealed cleaning housing, comprises a cleaningstep whereby various chemical fluids are sequentially supplied fromabove to the front face of each wafer, which is rotatably supported bythe wafer rotary means in the cleaning housing, originating from supplynozzles located on the upper side of the cleaning housing, whilepurified water is injected and supplied to the back face of each waferat the same time from a supply nozzle located on the lower side of thecleaning housing.

In the preferred embodiment, when purified water is injected andsupplied in a radial direction from the lower side supply nozzle to thecentral portion of the back face of each wafer, which is rotatablysupported by the wafer rotary means in the cleaning housing, theinjected purified water cleans the back face of each wafer while itflows in a radial direction to the back face of the wafer owing to thecentrifugal force generated by the rotation of each wafer. In addition,the injection and supply of purified water from the lower side supplynozzle is intended to cause the wafer to float owing to the force ofinjection and to reach the outer peripheral portion of the back face ofthe wafer owing to the centrifugal force generated by the rotation ofthe wafer.

The single wafer type cleaning apparatus of the invention is suitablefor carrying out the foregoing cleaning method, and is designed to cleanwafers, which are not stored in a cassette, one by one in a sealedcleaning housing, wherein the cleaning apparatus comprises (1) a waferrotary means for supporting and rotating each wafer in the cleaninghousing in the horizontal position, (2) a cleaning chamber provided atthe outer peripheral portion of the wafer rotary means for forming acleaning treatment space to clean each wafer which is rotatablysupported by the wafer rotary means, (3) a chemical fluid supply meansfor supplying chemical fluids to the front face of each wafer which isrotatably supported by the wafer rotary means, (4) a purified watersupply means for supplying purified water to the back face of each waferwhich is rotatably supported by the wafer rotary means, wherein severalchemical fluids are sequentially supplied from the chemical fluid supplymeans to the front face of each wafer from above, while the wafer isrotatably supported by the wafer rotary means, and at the same timepurified water is injected and supplied from the purified water supplymeans to the back face of each wafer.

In the preferred embodiment of the invention, the purified water supplymeans has an injection nozzle for injecting and supplying purified waterto the back face of the wafer which is rotatably supported by the waferrotary means, wherein the injection nozzle is directed upward andlocated on the upper end portion of the rotatable rotary shaft of thewafer rotary means and can communicate with the purified water supplysource. Further, the injection nozzle comprises a storage sectioncommunicating with the first and second passages and a number ofinjection ports located in the storage section.

Under the single wafer type cleaning system of the invention, severalchemical fluids are sequentially supplied from the upper side supplynozzle to the front face of each wafer which is rotatably supported bythe wafer rotary means while purified water is injected and suppliedfrom the lower side supply nozzle to the back face of each wafer whilethe front face of the wafer is being cleaned by chemical fluids. As aresult, it is possible to design a single wafer type wet-cleaningtechnique capable of effectively preventing the chemical fluids fromflowing to the back face of each wafer when the front face of the wafer,which is not stored in a cassette, is cleaned by the chemical fluids inthe sealed cleaning chamber. In the process, the chemical fluids thatare supplied to the front face of each wafer flow toward the outerperipheral portion of the face of the wafer owing to the centrifugalforce generated by the rotation of the wafer and are therefore prone toflow to the back face of the wafer. Accordingly, when the front face ofeach wafer is cleaned by chemical fluids, and purified water is injectedand supplied to the back face of the wafer, the chemical fluids flow ina radial direction along the back face of the wafer owing to thecentrifugal force generated by the rotation of the wafer, therebycleaning the back face of the wafer. The purified water thus provides asealing function relative to the chemical fluids which are prone to flowfrom the front face of the wafer to the back face thereof, and in theprocess effectively prevents the back face of the wafer from beingcontaminated by the chemical fluids.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front sectional view showing the internal structure of thesingle wafer type substrate cleaning apparatus according to thepreferred embodiment of the invention;

FIG. 2 is an enlarged sectional front view showing the locationalrelationship between the wafer rotary section, the cleaning housing andthe chemical fluid supply section of the single wafer type substratecleaning apparatus;

FIG. 3 is a front view showing the construction of the wafer rotarysection and the lower side injection nozzle of the purified water supplysection;

FIGS. 4 is an enlarged front sectional view showing the construction ofthe wafer rotary section and the peripheral portion of the lower sideinjection nozzle of the purified water supply section;

FIGS. 5(a), 5(B) and 5(C) are enlarged plan views showing modifiedexamples of the arrangement of injection ports of the lower sideinjection nozzle;

FIG. 6 is an enlarged front sectional view showing the mechanism forpreventing the chemical fluids from flowing to the back face of thewafer by the injection and supply of purified water from the lower sideinjection nozzle in FIG. 3; and

FIGS. 7(A) and 7(B) are views showing the construction for preventingthe chemical fluids from flowing to the back face of each wafer in theconventional single wafer type substrate cleaning apparatus, whereinFIG. 7(A) is a front sectional view of the same construction and FIG.7(B) is an enlarged front sectional view showing the mechanism forpreventing the chemical fluids from flowing to the back face of eachwafer by the injection and supply of a gas from the lower side annularnozzle in the construction of FIG. 7(A).

PREFERRED EMBODIMENT OF THE INVENTION

The preferred embodiment of the invention is described with reference tothe attached drawings.

A single wafer type wet-cleaning apparatus is illustrated in thedrawing, wherein each wafer W, which is not stored in a cassette, iswet-cleaned individually in a sealed cleaning housing 1, and thesealable cleaning housing 1 comprises a wafer rotary section (waferrotary means) 2 for rotatably supporting one wafer W in the horizontalposition, a cleaning chamber 3 which is relatively vertically movable, achemical fluid supply section (chemical fluid supply means) 4 forsupplying chemical fluids to the front face Wa of the wafer, a purifiedwater supply section (purified water supply means) 5, an inert gassupply section (inert gas supply means) 6 for supplying an inert gas forpreventing oxidation, and a controller 7 for controlling these drivingsections while interlocking mutually therewith as major components.

The cleaning housing 1 is sealable at the upper portion for the cleaningtreatment and serves as a location for installing various unit drivingsections at the lower portion disposed in the upper space. A closablewafer taking in-out port, not shown in detail, through which the wafer Wis taken in or taken out in the upper space of the cleaning housing 1,is structured in such a way to secure airtightness and watertightnesswhen it is closed.

The wafer rotary section 2 horizontally rotates a single wafer W whileit supports the single wafer W in the horizontal position when the spincleaning and spin drying treatments are applied thereto, and comprises arotary shaft 10, a wafer supporting section 11 which is attached to andsupported by the upper end portion of the rotary shaft 10 in thehorizontal position, and a driving motor 12 for rotatably driving therotary shaft 10.

The wafer supporting section 11 and the rotary shaft 10 are rotatablydisposed at the center of the cleaning housing 1 via a bearingsupporting cylinder 13 in a perpendicular position, and a single wafer Wcan be supported by the wafer supporting section 11 in the horizontalstate.

In particular, the wafer supporting section 11 comprises a discoid bodyhaving annular wall section 11 a which stands upright at its outerperipheral portion, as shown in FIGS. 2 and 3, and has a number ofcolumnar supporters, 14, 14, . . . on the annular wall section 11 a(four of which are shown in FIG. 4) for placing and supporting the waferW on the peripheral portion of the upper face thereof.

These supporters 14, 14, . . . are circumferentially arranged on thewafer supporting section 11 at the same intervals as illustrated inFIGS. 2 and 3, and the inner peripheral portions of the tips thereofsupport the outer peripheral portion Wc of each wafer W to formsupporting recesses 14 a, 14 a, . . . . The supporting recesses 14 a, 14a, . . . of these supporters 14, 14, . . . are designed to have the sameheight, so that the peripheral portion of the wafer W is supported whenit is placed thereon in the horizontal position.

Further, the supporting face of each supporting recess 14 a has aconfiguration corresponding to the contour of the peripheral portion ofthe wafer W in cross section, and the peripheral edge corner section ofeach supporting recess can contact and support the square peripheralcorner of the wafer W in cross section in a point contact state or linecontact state.

As shown in FIGS. 1 and 2, the rotary shaft 10 is rotatably supported bythe bearing supporting cylinder 13 in the standing position, and thelower end portion of the rotary shaft 10 is connected to the drivingmotor 12 so as to be rotatably driven by the driving motor 12 via a beltentrained therebetween so that the wafer supporting section 11 isrotated at a given speed of rotation. The speed of rotation of therotary shaft 10 is set at low speed, e.g., 40-50 r.p.m. when the spincleaning treatment is effected while it is set at high speed ofapproximately 3000 r.p.m. when the spin drying treatment is effected.

Further, the rotary shaft 10 comprises a hollow cylindrical body asillustrated, and a pipe 30 for the lower side nozzle 26 of the purifiedwater supply section 5, described later, is disposed in the hollowsection of the rotary shaft 10.

The cleaning chamber 3 is the section where the cleaning treatment isapplied to the wafer W, and the inner diameter dimensions thereof aredetermined in connection with the wafer supporting section 11 of thewafer rotary section 2, described hereinbelow, and has a cleaningtreatment space for the wafer W, which is rotatably supported by thewafer rotary section 2, at the outer periphery of the wafer rotarysection 2.

In detail, the cleaning chamber 3 is partitioned as shown in FIGS. 1 and2 to define plural stages of annular treatment baths 15 to 18 which arearranged vertically at the inner periphery thereof as shown in FIGS. 1and 2, and is constructed to move up and down vertically relative to thewafer rotary section 2.

In the illustrated preferred embodiment, four stages of annulartreatment baths 15 to 18 are arranged vertically and concentrically withthe wafer W so as to surround the wafer W which is supported by thewafer supporting section 11 of the wafer rotary section 2.

The peripheral inner edges of the annular treatment baths 15 to 18 arearranged in the manner that annular gaps defined between these edges areset to have small intervals to such extent as would prevent the chemicalfluids and the like from being leaked downward and at the same time donot contact the outer diameter edge of the wafer supporting section 11of the wafer rotary section 2.

The cleaning chamber 3 is constructed to be movable up and down, i.e.,vertically via an elevating guide (not shown), and has an elevatingmechanism 20 capable of elevating relative to the wafer supportingsection 11 of the wafer rotary section 2 by a given stroke.

The elevating mechanism 20 comprises a feed screw mechanism (not shown),which moves a supporting frame 21 for supporting the cleaning chamber 3up and down, and a driving motor 22 for rotatably driving the feed screwmechanism.

Depending on the cleaning treatment step, the cleaning chamber 3 movesup and down vertically by a given stroke via the feed screw mechanism asthe driving motor 22 is driven while interlocking with the operation ofthe wafer rotary section 2, described hereinbelow, so that any one ofthe annular treatment baths 15 to 18 for effecting the cleaningtreatment step may be selected from a position of height relative to thewafer W which is supported by the wafer supporting section 11 of thewafer rotary section 2.

Drain sections, which communicate with the outside of the apparatus, arerespectively provided in the four annular treatment baths 15 to 18 (notillustrated in detail). These drain sections discharge or collect forrecycling the chemical fluids or the inert gas inside the annulartreatment baths 15 to 18, in which they are structured to be opened onlywhen the cleaning treatment is effected and to be closed when thecleaning treatment is effected in the other treatment baths.

The chemical fluid supply section 4 supplies the chemical fluids to theface Wa of the wafer W which is rotatably supported by the wafer rotarysection 2, and it has upper side supply nozzles 25 as its maincomponents for supplying the chemical fluids to the front face of thewafer W from above.

In detail, the upper side supply nozzles 25 consist of injection nozzlesdesigned to inject and supply the chemical fluids to the front face ofthe wafer W, whereby the number of nozzles to be employed depends on thekind of chemical fluids to be supplied, and the upper side supplynozzles can communicate with the chemical fluid supply source 27provided outside the cleaning housing 1.

In the illustrated embodiment, the upper side injection nozzles 25 arelocated in the injection nozzle section 25A which integrally consists ofa plurality of nozzle sections, and the injection nozzle section 25A isconstructed in such a manner that it may be turned horizontally in adownward direction at the upper portion of the cleaning housing 1, andit is drivably connected to a driving motor capable of being swung (notshown).

The injection nozzles to be utilized depends on the kind of cleaningfluids to be supplied. In particular, these upper side injection nozzles25, 25, . . . (only one is illustrated in FIG. 2) which are provided inthe injection nozzle section 25A (not shown), are intended to serve assupply ports for an APM fluid, purified water and a DHF fluid, describedhereinbelow.

The upper side injection nozzles 25 or the injection nozzle section 25Aare constructed in such a way as to inject and supply given chemicalfluids to the front face Wa of the wafer W which is rotatably supportedby the wafer supporting section 11 of the wafer rotary section 2 in thehorizontal position while it is turned horizontally from the outerregion toward the center thereof or when it stands still after beingturned horizontally.

The chemical fluid supply source 27 is the supply source for supplyingcleaning chemical fluids to the upper side injection nozzles 25 and hastwo chemical fluid systems, as shown in the illustrated embodiment,either of which may be selected to clean the wafer W. One system employsan APM (NH₄OH+H₂O₂; H₂O) fluid while the other system uses a DHF(HF+H₂O) fluid, whereas annular treatment baths 15 to 18 in the cleaningchamber 3 correspond with these two chemical fluid supply systems, suchthat, the lowermost stage treatment bath 15 is used for the cleaningstep by APM fluid, the third upper stage treatment bath 16 is used forthe cleaning step by DHF fluid, the second upper stage treatment bath 17is used for the rinsing step by purified water, and the uppermost stagetreatment bath 18 is used for the spin drying step.

Further, the chemical fluid supply source 27 is constructed to selectand effect the cleaning steps using any of the following recipes ofchemical fluids: i) APM+DHF+(O₃+DIW)+DRY; ii) APM+DHF+DRY; iii) APM+DRY,DHF+DRY or the like with the cooperation of the inert gas supply source37 described hereinbelow.

In particular, the upper side injection nozzles 25 are controlled insuch a manner that they subsequently supply a plurality of chemicalfluids from above to the front face Wa of each wafer W, which isrotatably supported by the wafer rotary section 2, in accordance withthe recipe which was selected from any of the abovementionedcombinations i) to iii), thereby cleaning the wafer W while purifiedwater is supplied from the lower side supply nozzle 26 in a series ofcleaning steps.

The inert gas supply section 5 supplies purified water to the back faceWb (lower surface in the drawings) of each wafer W which is rotatablysupported by the wafer rotary section 2 and comprises as its maincomponent a lower side supply 26 for supplying purified water to theback face Wb of the wafer W from the lower side.

In detail, the lower side injection nozzle 26 comprises an injectionnozzle for supplying purified water to the back face Wb of the wafer W,and it can communicate with the purified water supply source 28 which isprovided outside the cleaning housing 1.

In the illustrated embodiment, the lower side injection nozzle 26 isprovided at the upper end portion of the rotatable rotary shaft 10 ofthe wafer rotary section 2, and it is directed upward in a fixedposition relative to the back face Wb of the wafer W which is rotatablysupported by the wafer rotary section 2. The lower side injection nozzle26 comprises a storage section 50, and a plurality of injection ports51, 51, . . . which are provided in the storage section 50, wherein thestorage section 50 can communicate with the purified water supply source28 via the pipe 30 which is disposed inside the rotary shaft 10.

The injection ports 51, 51, . . . are linearly arranged to extend in aradial direction as shown in FIG. 3 according to the illustratedembodiment, but they may be arranged in the manner as illustrated inFIGS. 5(A), 5(B) and 5(C).

The arrangement of the injection ports 51, 51, . . . as shown in FIGS.5(A), 5(B) and 5(C) is such that the sum of the areas of the openings ofthe injection ports 51, 51, . . . becomes larger at the outer region ofthe face of each wafer than at the center thereof as they direct towardthe outer region of the wafer. Such an arrangement is very effective ifpurified water supplied in a radial direction from the lower sideinjection nozzle 26 to the center of the back face Wb of the wafer W ina radial direction flows to the back face Wb of the wafer W owing to thecentrifugal force generated by the rotation of the wafer W.

The injection ports 51, 51, . . . shown in FIG. 5(A) are in the form ofcircular arc slits, and the length and width dimensions thereof aredesigned to be larger at the outer region of the wafer W than at thecenter thereof as the injection openings direct toward the outer regionsof the wafer W. Further, the injection ports 51, 51, . . . shown in FIG.5(B) are in the form of radially extended slits, and the widthdimensions thereof are designed to be larger at the outer region of thewafer W than at the center thereof as the injection openings directtoward the outer regions of the wafer W. Further, the injection ports51, 51, . . . shown in FIG. 5(C) are in the form of circular openingswhich are arranged circumferentially and radially at prescribedintervals, and the diameter dimensions thereof are designed to be largerat the outer region of the wafer W than at the center thereof as theinjection openings direct toward the outer regions of the wafer W.

The pipe 30 vertically penetrates the hollow section of the rotary shaft10 composed of a hollow cylindrical body, and is firmly disposed on therotary shaft 10 by a supporting mechanism (not shown), while it does notcontact the rotary shaft 10.

A discoid drainage receiver 31 is integrally provided on the upper endportion of the pipe 30, and the lower side injection nozzle 26 isprovided at the center of the drainage receiver 31. The storage section50 of the lower side injection nozzle 26 communicates with severalpurified water supply passages (through a pipe for supplying purifiedwater) 30 a, 30 a, . . . which are provided by penetrating the interiorof the pipe 30.

The upper face of the drainage receiver 31 is disposed to be flush withthe upper face of the annular wall section 11 a of the wafer supportingsection 11 , and the outer diameter edge of the drainage receiver doesnot contact the inner diameter face of the annular wall section 11 a. Anannular gap 45 defined between the outer diameter edge of the drainagereceiver 31 and the inner diameter face of the annular section 11 a isdesigned to be very small to such extent as would prevent the chemicalfluids and the like from leaking downward.

Further, the purified water supply passages 30 a, 30 a, . . . canselectively communicate with the purified water supply source 28 via thedirectional control valve 32 at the lower end portion of the pipe 30.

Purified water which is supplied from the purified water supply source28 and is injected in a radial direction through the lower sideinjection nozzle 26 to the center of the back face Wb of the wafer W,which is rotatably supported by the wafer supporting section 11 of thewafer rotary section 2, then flows in a radial direction along the backface Wb of the wafer w owing to the centrifugal force generated by therotation of the wafer W.

The supply of purified water from the purified water supply source 28and the injection of the same through the lower side injection nozzle 26in the illustrated embodiment has the effect of floating the wafer wwhich is rotatably supported by the wafer supporting section 11 of thewafer rotary section 2 and reaches the outer peripheral portion of thewafer W along the back face wb owing to the centrifugal force generatedby the rotation of the wafer W.

The purified water supply source 28 is drivably controlled such that thesupply of purified water from the lower side injection nozzle 26 issynchronized with the cleaning of the front face Wa of the wafer W bychemical fluids from the chemical fluid supply section 4. In otherwords, if purified water is injected and supplied to the back face Wb ofthe wafer W from the lower side injection nozzle 26 in accordance withthe foregoing determined conditions, the purified water cleans the backface Wb of the wafer W and at the same time prevents the chemical fluidsfrom flowing to the back face Wb of the wafer W.

The Chemical Fluid Flowing Around Prevention Technique is describedhereafter with reference to FIG. 6. The chemical fluids supplied to thefront face Wa of the wafer W flow toward the outer peripheral portion Wcof the wafer W owing to the centrifugal force generated by the rotationof the wafer W, and are therefore prone to flow back to the back facefrom the outer peripheral portion Wc. However, the injection and supplyof purified water to the back face Wb of the wafer W cleans the samewhile flowing in a radial direction along the back face Wb owing to thecentrifugal force generated by the rotation of the wafer W and therebyisolates the chemical fluids which are prone to flow from the front faceWa to the back face Wb, thereby effectively preventing contamination ofthe back face Wb by the chemical fluids.

The inert gas supply section 6 supplies an inert gas for preventingoxidation toward the front and back faces of each wafer W which isrotatably supported by the wafer rotary section 2 and comprises, asmajor components, an upper side supply section 35 for supplying an inertgas to the front face Wa of each wafer W and a lower side supply section36 for supplying inert gas to the back face Wb of each wafer, whereinthese upper and lower side supply sections 35 and 36 can communicatewith the inert gas supply source 37 provided outside the cleaninghousing 1. In the illustrated preferred embodiment, the inert gas is anitrogen gas (hereinafter, the “N₂ gas”).

The inert gas supply section 6 supplies N₂ gas for preventing oxidationtoward the front and back faces of each wafer W which is rotatablysupported by the wafer rotary section 2 and comprises, as majorcomponents, an upper side supply section 35 for supplying N₂ gas to thefront face of each wafer W and a lower side supply section 36 forsupplying N₂ gas to the back face of each W, wherein these upper andlower side supply sections 35 and 36 can communicate with the insert gassupply source 37 provided outside the cleaning housing 1.

The upper side supply section 35 is provided at the upper portion of thecleaning housing 1 and comprises a circular cover body for forming adrying sealed space at the periphery of the front face Wa of each waferW which is rotatably supported by the wafer rotary section 2 whilecooperating with the cleaning chamber 3.

In detail, the outer diameter edge of the upper side supply section 35is designed to closely engage with the inner diameter edge of thecleaning chamber 3, i.e., the outer diameter edge of the uppermost stagetreatment bath 18, so that the requisite minimum drying sealed space isformed at the periphery of the front face Wa of each wafer W which isrotatably supported by the wafer rotary section 2. The upper side supplysection 35 communicates with the inert gas supply source 37 via a pipe38.

The upper side supply section 35 is vertically movable between the useposition (not shown) cooperating with the cleaning chamber 3 and the usestandby position, i.e., the position of height shown in FIG. 1 whichdoes not interfere with the chemical fluid supply section 4, and isdrivably connected to an elevating means, not shown.

The lower side supply section 36 is provided on the upper end portion ofthe rotatable rotary shaft 10 of the wafer rotary section 2. As shown inFIG. 4, the lower side supply section 36 is composed of the lower sideinjection nozzle 26 which is constructed in such a way as to likewiseserve the purified water supply section 5, and an upper end gap 39defined between the hollow inner periphery of the upper end portion ofthe rotary shaft 10 and the outer periphery of the pipe 30.

The lower side injection nozzle 26 is housed in the storage section 50,as set forth above, and communicates with the inert gas supply source 37via the pipe 30 disposed inside the rotary shaft 10.

In particular, an inert gas supply passage (i.e., a pipe for supplyinginert gas) 30 b penetrates the interior of the pipe 30 and is arrangedparallel to the purified water supply passages 30 a, wherein the upperend of the inert gas supply passage 30 b communicates with the storagesection 50 of the lower side injection nozzle 26, and the lower endthereof can selectively communicate with the inert gas supply source 37via a directional control valve 52.

The upper end gap 39 serving as another supply port of the lower sidesupply section 36 is positioned at and opens to a space 53 definedbetween the drainage receiver 31 and the wafer supporting section 11, asshown in FIGS. 2 and 4, and can selectively communicate with the inertgas supply source 37 via the directional control valve 52.

Through the inert gas supply section 6, the upper side supply section 35thereof injects and supplies N₂ gas when the wafer W is cleaned and thechemical fluid inside the cleaning chamber 3 is drained or replaced withanother chemical fluid.

Meanwhile, the lower side injection nozzle 26 of the lower side supplysection 36 injects and supplies purified water from the purified watersupply source 28 when the wafer W is cleaned, and injects and suppliesN₂ gas in synchronization with the operation of the upper side supplysection 35 at other times when the directional control valves 32 and 52are switched.

Further, the upper end gap 39 of the lower side supply section 36functions in the same manner as the upper side supply section 35, byinjecting and supplying N₂ gas when the wafer is cleaned and thechemical fluid inside the cleaning chamber 3 is drained or replaced withanother chemical fluid, so that any particles remaining in the space 53defined between the drainage receiver 31 and the wafer supportingsection 11 are purged and replaced by N₂ gas to maintain the positivepressure on the space 53, thereby effectively preventing the chemicalfluids and purified water from leaking downward through the annular gap45.

The controller 7 controls the movements of the components of the singlewafer type substrate cleaning apparatus while interlocking with thesecomponents, thereby automatically effecting the following series of wettreatment steps:

-   -   (1) Prior to the application of the cleaning treatment, the        wafer W is taken in the wafer supporting section 11 inside the        cleaning chamber 3 via the wafer taking in/out port of the        cleaning housing 1 (not shown), and after the cleaning chamber        is sealed, the wafer W is placed in the cleaning treatment        position inside the cleaning chamber 3 by the up and down        movement of the cleaning chamber 3. Thereafter, the foregoing        various cleaning treatments are effected in a predetermined        procedure.    -   (2) For example, if the cleaning treatment is in the        foregoing ii) cleaning treatment step (APM+DHF ; DRY), the wafer        W on the wafer supporting section 11 is first positioned and        disposed in the lowermost stage treatment bath 15 and while the        cleaning chamber 3 moves up and down the APM fluid is supplied        from the upper side injection nozzles 25, and the spin cleaning        treatment is applied to the wafer W as the wafer rotary section        2 rotates at low speed.

Purified water is injected and supplied from the lower side injectionnozzle 26 to the back face Wb of the wafer W in synchronization with thespin cleaning treatment effected by the APM fluid, thereby cleaning theback face wb of the wafer W and preventing the APM fluid from flowing tothe back face Wb thereof.

-   -   (3) Subsequently, the wafer W is positioned and disposed in the        second upper stage treatment bath 17, and purified water is        injected and supplied from the upper side injection nozzles 25        while the rinsing treatment is applied to the wafer W as the        wafer rotary section 2 rotates at low speed.

Also, in this case, purified water is injected and supplied from thelower side injection nozzle 26 to the back face Wb of the wafer W insynchronization with the rinsing treatment, thereby cleaning the backface Wb of the wafer W and preventing the rinsing water from flowing tothe back face wb of the wafer W.

-   -   (4) Further, the wafer W is positioned and disposed in the third        upper stage treatment bath 16, and the DHF fluid is supplied        from the upper side injection nozzle 25 while the spin cleaning        treatment is applied to the wafer W as the wafer rotary section        2 rotates at low speed.

Purified water is injected and supplied from the lower side injectionnozzle 26 to the back face Wb of the wafer W in synchronization with thespin cleaning treatment by the DHF fluid, thereby cleaning the back faceWb of the wafer W and preventing the DHF fluid from flowing to the backface Wb thereof.

-   -   (5) Further, the wafer W is positioned and disposed in the        second upper stage treatment bath 17, and purified water is        supplied from the upper side injection nozzle 25 while the        rinsing treatment by purified water is applied to the wafer W as        the wafer rotary section 2 rotates at low speed, and purified        water is injected and supplied from the lower side injection        nozzle 26 to the back face Wb of the wafer W, thereby cleaning        the back face Wb of the wafer W and preventing the rinsing water        from flowing from the front face Wa of the wafer W to the back        face wb thereof.    -   (6) Finally, the wafer W is positioned and disposed in the        uppermost stage treatment bath 18, while N₂ gas is injected from        the upper side supply section 35 and the lower side supply        section (i.e., the lower side injection nozzle 26) of the inert        gas supply section 6, and the spin drying treatment is applied        to the wafer W as the wafer rotary section 2 rotates at high        speed.

In the drying step, the upper side supply section 35 of the inert gassupply section 6 is lowered to the use position while cooperating withthe cleaning chamber 3, so that it forms a drying sealed space whilecooperating with the cleaning chamber 3, and thereafter N₂ gas issupplied to and fills the drying sealed space.

Accordingly, when contents of the drying sealed space A are purged andreplaced by the N₂ gas, or, when occasion demands, air current isproduced in the passage extending from the inert gas supply section 6 tothe drain section inside the drying sealed space owing to the forcefulair discharge from the drain section of the uppermost stage treatmentbath 18, the concentration of oxygen on the periphery of the entirefront face Wa of the wafer W becomes substantially zero (0), andthereafter the spin drying treatment is applied to the wafer W.

-   -   (7) The wafer W is again taken out via the wafer taking in/out        port of the cleaning housing 1 upon completion of a series of        cleaning treatments in the single wafer type cleaning apparatus.

Under the single wafer type substrate cleaning apparatus having theforegoing construction, a plurality of chemical fluids is sequentiallysupplied vertically from the upper side injection nozzles 25 to thefront face Wa of a single wafer W which is rotatably supported in thesealed cleaning housing 1 so as to wet-clean it, while purified water isinjected and supplied from the lower side supply 26 to the back face Wbof the wafer W when the wet-cleaning treatment is applied to the frontface Wa thereof, thereby cleaning the back face Wb and preventing thechemical fluids from flowing to the back face Wb of the wafer W.

In other words, owing to the centrifugal force generated by the rotationof the wafer W, the chemical fluids supplied to the front face Wa of thewafer W flow toward the outer peripheral portion of the wafer W and theyare prone to flow from the outer peripheral portion of the wafer W tothe back face Wb thereof. Accordingly, as the front face Wa of the waferW is cleaned by chemical fluids, purified water is injected and flows ina radial direction along the back face Wb of the wafer W owing to thecentrifugal force generated by the rotation of the wafer W, therebycleaning the back face Wb, and provides a sealing function relative tothe chemical fluids which are prone to flow from the front face Wa tothe back face Wb, thereby effectively preventing contamination of theback face Wb of the wafer W by the chemical fluids.

Although the foregoing embodiment is the preferred embodiment of theinvention, the invention is not limited thereto but can be redesignedand modified within the scope of the invention.

For example, the single wafer type cleaning apparatus can be used as asingle apparatus, or as a basic construction element of a wafer cleaningsystem provided with a loading section, an unloading section or othertypes of equipment such as placing and mounting robots and the like.

Further, the chemical fluids employed by the embodiment are merelysamples, and hence other chemical fluids such as HPM (HCL+H₂O₂+H₂O), SPM(H₂SO₄+H₂O₂+H₂O) and the like can be used depending on the objectthereof.

Further still, in the illustrated embodiment, purified water supplypassages 30 a, 30 a, . . . which communicate with the lower sideinjection nozzle 26 may be constructed in such a manner as tocommunicate either with the purified water supply source 28 or thechemical fluid supply source 27 via the directional control valve 32,thereby applying either the single side cleaning treatment to the frontface Wa of the wafer W as illustrated in the drawings or dual sidecleaning treatment to the wafer W, i.e., the front face Wa and back faceWb of the wafer W.

1. A single wafer type substrate cleaning apparatus for cleaning wafersindividually, which are not stored in a cassette, in a sealed cleaninghousing, said apparatus comprising: wafer rotary means for supportingand rotating a single wafer in the cleaning housing in a horizontalposition; a vertically movable, partitioned cleaning chamber provided atan outer peripheral portion of the wafer rotary means for forming aplurality of selectively operable cleaning treatment spaces forcleaning, in sequential stages, each wafer which is rotatably supportedby the wafer rotary means; chemical fluid supply means for supplyingchemical fluids to a front face of each wafer which is rotatablysupported by the wafer rotary means; purified water supply means forsupplying purified water to a back face of each wafer which is rotatablysupported by the wafer rotary means; means for sequentially supplying aplurality of chemical fluids from the chemical fluid supply means to thefront face of each wafer from above, which wafer is rotatably supportedby the wafer rotary means, and means for simultaneously injecting andsupplying purified water from the purified water supply means to theback face of each wafer.
 2. The single wafer type substrate cleaningapparatus according to claim 1, wherein the purified water supply meanshas an injection nozzle for injecting and supplying purified water tothe back face of each wafer which is rotatably supported by the waferrotary means, and wherein the injection nozzle is directed upward andlocated on an upper end of a rotatable rotary shaft of the wafer rotarymeans and can communicate with a purified water supply source.
 3. Thesingle wafer type substrate cleaning apparatus according to claim 2,wherein the rotary shaft of the wafer rotary means consists of a hollowcylindrical body, and a first supply passage, which can communicate withthe purified water supply source and thereby supply the purified water,whereby said first supply passage vertically penetrates a hollow sectionof the rotary shaft firmly without contacting the rotary shaft, and theinjection nozzle is a lower side supply nozzle which is directed upwardand located on an upper end portion of the first supply passage forsupplying purified water.
 4. The single wafer type substrate cleaningapparatus according to claim 3, including a second supply passage forsupplying an inert gas operative to communicate with the first supplypassage for supplying purified water and with an inert gas supplysource, whereby said second supply passage penetrates the hollow sectionof the rotary shaft concentrically without contacting the rotary shaft,and the lower side supply nozzle is directed upward and is located onthe upper end portions of the first and second supply passages,respectively, and is operative for supplying purified water and theinert gas.
 5. The single wafer type substrate cleaning apparatusaccording to claim 4, wherein the injection nozzle comprises a storagesection communicating with the first and second supply passages and aplurality of injection ports provided in the storage section.
 6. Thesingle wafer type substrate cleaning apparatus according to any ofclaims 2 to 5, wherein the injection nozzles can communicate either withthe purified water supply source or a chemical fluid supply source ofthe chemical fluid supply means whereby either a singular side cleaningtreatment to the front face of each wafer is applied, or a dual sidecleaning treatment, to the front and back faces of each wafer, throughthe chemical fluid supply means.
 7. The apparatus according to claim 6,wherein a gap defined between an inner periphery of the rotary shall ofthe wafer rotary means and an outer periphery of the first and secondsupply passages serves as a supply port of an inert gas.
 8. Theapparatus according to claim 7, wherein the cleaning chamber is movableup and down relative to the wafer rotary means, and several annulartreatment baths forming a cleaning treatment space are arrangedvertically and concentrically with an inner peripheral portion of thecleaning chamber so as to surround each wafer supported by the waferrotary means, and wherein, depending on a selected cleaning treatmentstep, one of the annular treatment baths is moved to a positioncorresponding to each wafer supported by the wafer rotary means as thecleaning chamber moves up and down.
 9. The apparatus according to claim8, wherein the cleaning chamber is designed in such a way that an innerperipheral edge of each annular treatment bath does not contact an outerperipheral edge of a wafer supporting section of the wafer rotary means,and the gap defined between these edges is annular and is designed to bevery small in order to prevent the chemical fluids and purified waterfrom leaking downward.